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ITRON History ITRON1 – designed for 8 and 16 bit MCU ITRON2 – support 32 bit MCU μITRON2 – adaptation for low-cost MCU μITRON3 – scalability enhancements μITRON4 – compatibility enhancement Targeted for 32 bit MPU The first spec for ITRON Kernel Targeted for 8-bit and 16-bit MCU Scalability Enhancement Compatibility Enhancement Copyright © 2011 DSR Corporation 1
ITRON Usage (cont. ) Copyright © 2011 DSR Corporation 2
Configure the System RTOS configuration file Source files for the task Source files for the interrupt handler Configurator Compiling and linking Software Components Object file To ROM RTOS Libraries Software Components Other Libraries.c and.h files are generated as a result of configurator functioning Copyright © 2011 DSR Corporation 3
Task States (cont.) Copyright © 2011 DSR Corporation 4
Scheduling Rules (cont.) Scheduling example Task A of the highest priority Task B, C, D of the middle priority Task E of the lowest priority Workflow Task A terminates, task B moves to RUNNING state If task B goes to WAITING or SUSPENDEND state and then back to READY, it has the lowest precedence If Task A is reactivated, Task B is pre-empted and return to the READY state, it has the highest precedence Copyright © 2011 DSR Corporation 5
Dispatch Pending State Dispatch does not occur (dispatch pending state) – During execution of processing units with higher precedence than that of the dispatcher – The CPU in locked state – Dispatch disabled state Task state transition into SUSPENDED or DORMANT state is hold until dispatch is turned on – Task state transition may be done using service calls from non-task context Low priority task A is running Dispatch pending state during interrupt handler execution High priority task B is activated from interrupt handler Task state changes only after dispatcher executes Copyright © 2011 DSR Corporation 6
Semaphore (cont.) Semaphore usage example Semaphore acquire req. Semaphore acquired Semaphore (SID1) Work with shared resources Release semaphore Semaphore acquire req. Work with shared resources Sem. resource number = 0 Sem. resource number = 1 Start Semaphore acquired Dispatch Wait release, dispatch Task 1 (Priority: Low) Task 2 (Priority: High) Copyright © 2011 DSR Corporation 7
Eventflag (cont.) Eventflag usage example Event flag is cleared Set event flag 01 Release waiting flag=01 flag=00 Wait for event 11 Starting Dispatch Wait release, dispatch Task 1 (Priority: Low) Eventflag Task 2 (Priority: High) Copyright © 2011 DSR Corporation 8
Data Queue (cont.) Data queue functioning example: wait for receive Empty queue Data queue Receive message Release waiting Send message Wait release, dispatch Task 1 (Priority: Low) Task 2 (Priority: High) Dispatch Receive wait Copyright © 2011 DSR Corporation 9
Data Queue (cont.) Data queue functioning example: asynchronous send 1 message in queue Start Task 1 (Priority: Low) Data queue Task 2 (Priority: High) Time Send a message Empty queue Receive message Empty queue Copyright © 2011 DSR Corporation 10
Data Queue (cont.) Data queue functioning example: wait for send Queue is full Send a message Receive message Data queue Put data to queue Send-wait state Dispatch Wait release, dispatch Task 1 (Priority: Low) Data queue Task 2 (Priority: Low) Copyright © 2011 DSR Corporation 11
References μITRON4.0 Specification _en.pdf _en.pdf RTEMS ITRON 3.0 Users Guide eCOS μITRON API ITRON short description FAQ of ITRON Specification OS TOPEERS/JSP Copyright © 2011 DSR Corporation 12
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